Synergistic organotin stabilizer compositions and resins stabilized therewith

ABSTRACT

WHEREIN R3 IS A HYDROCARBYL RADICAL HAVING 1 TO 12 CARBON ATOMS, Z AND Z1 ARE EITHER OXYGEN OR SULFUR, R4 IS HYDROGEN OR AN ORGANIC RADICAL BONDED TO Z1 BY A CARBON ATOM AND N IS A NUMBER FROM 0 TO 1 1/2 VARYING IN INCREMENTS OF 1/2. HALIDE CONTAINING RESINS STABILIZED WITH THESE COMPOSITIONS EXHIBIT IMPROVED RESISTANCE TO THE DEVELOPMENT OF EARLY COLOR DURING PROCESSING.   R3SN(X)N(Z1R4)3-2N   AN IMPROVED STABILIZER COMPOSITION COMPRISES A SYNERGISTIC COMBINATION OF AN ORGANIC THIOANHYDRIDE AND A MONOHYDROCARBYL TIN COMPOUND OF THE FORMULA

United States Patent @lice 3,630,993 Patented Dec. 28, 1971 SYNERGISTICORGANOTIN STABILIZER COMPO- SITlONS AND RESINS STABILIZED THEREWITHChristian H. Stapfer, Newtown, Pa., assignor to Cincinnati MilacronChemicals, Inc., Reading, Ohio No Drawing. Filed Dec. 3, 1968, Ser. No.780,888 Int. Cl. C08f 45/62 U.S. Cl. 260-45.75 K 4 Claims ABSTRACT OFTHE DISCLOSURE An improved stabilizer composition comprises asynergistic combination of an organic thioanhydride and amonohydrocarbyl tin compound of the formula wherein R is a hydrocarbylradical having 1 to 12 carbon atoms, Z and Z are either oxygen orsulfur, R is hydrogen or an organic radical bonded to Z by a carbon atomand n is a number from to 1 /2 varying in increments of /2.

Halide containing resins stabilized with these compositions exhibitimproved resistance to the development of early color during processing.

This invention relates to organotin stabilizers and halide containingresins stabilized therewith. More particularly, the invention relates toa synergistic combination of organic thioanhydrides with monohydrocarbyltin compounds which reduces the development of early color duringprocessing when incorporated as a stabilizer in halogen containingresins.

During recent years the use of thioanhydrides corresponding to theformula 0 o R ii s (UJRZ wherein R and R are independently selectedhydrocarbon groups with 6 to 20 carbon atoms, have been contemplated asstabilizers against the thermal decomposition of halogen containingresins, and particularly polyvinyl chloride. These thioanhydrides aredesirable because they exhibit good long term stabilizing eflicacy forboth plastisized and rigid formations, but they have never gainedcommercial importance because of the substantial discoloration ofpolymers which occurs during processing. This discoloration is unrelatedto the stabilizing properties of the thioanhydrides, however, itseverely restricts the commercial use because of the serious detractionfrom the esthetic appeal of products.

I have discovered that organic thioanhydrides containing small amountsof monohydrocarbyl tin compounds corresponding to the formula R Sn(Z) (Z1R wherein R is a hydrocarbyl group containing 1 to 12 carbon atoms, Zand Z are independently selected from oxygen and sulfur, R is hydrogenor an organic radical bonded to Z by a carbon atom and n is a numberfrom 0 to 1 /2 varying in increments of /2 overcome the disadvantages ofthe prior art.

Suitable thioanhydrides for practicing the present invention includethose where R and R are the same or different alkyl or aryl radicals.The alkyl radicals may be straight chain radicals producing anhydridessuch as thiolauric or thiostearic anhydride; branched chain radicalsdride and unsaturated alkyl radicals such as those producing thiocrotonic anhydride. The aryl radicals suitable for practicing thepresent invention include unsubstituted aryl producing anhydrides suchas thiobenzoic anhydride or alkyl substituted aryl radicals producingthioanhydrides such as 2-tert.butylthiobenzoic anhydride. An example ofsuitable thioanhydrides which have different R and R groups isthiolauricbenzoic anhydride.

The monohydrocarbyl tin compounds suitable for arresting the developmentof early color on halogen con taining resins stabilized with organicthioanhydrides include stannoic oxides, stannoic sulfides, stannoicacids and thiostannoic acids having one hydrocarbyl group attached tothe tin atom. The hydrocarbyl group preferably contains 1 to 12 carbonatoms and may be an alkyl, aryl, alkaryl or aralkyl radical. Examples ofthis group of compounds include methylstannoic acid, methylthiostannoicacid, butyl stannoic acid, butyl thiostannoic acid, butyl tin sulfide,butyl tin oxide, n-octyl stannoic acid, isooctyl stannoic acid, n-octylthiostannoic acid, isooctyl thiostannoic acid and phenyl stannoic acid.These compounds frequently exist in the form of polymers which arecondensation products of the above stannoic and thiostannoic acids aswell as mixtures of stannoic and thiostannoic acids. The condensationproducts may contain 2 to 1000 repeat units and generally contain 2 torepeat units corresponding to the formula (R S Z wherein Z is oxygen,sulfur or a mixture of oxygen and sulfur, n equals 1.5 and y denotes thedegree of polymerization.

Monohydrocarbyl tin compounds suitable for practicing the presentinvention include compounds where R is a hydrocarbon radical, preferablyalkyl, having 1 to 12 carbon atoms. Some examples of suitable compoundsinclude the methyl, butyl, n-octyl and isooctyl esters of bothmonohydrocarbyl stannoic and thiostannoic acids such as the isooctylester of butylstannoic acid and the butyl ester of butylthiostannoicacid.

The monohydrocarbyl tin compounds can also have a functional groupattached to Z by a carbon atom and are useful in practicing the presentinvention. Functional groups of this type include wherein x is 1 to 3.Some examples of monohydrocarbyl tin compounds containing these groupsare monobutyl tin tris (isooctyl mercapto propionate), monobutyl tintris (isooctyl-3-mercapto butyrate) and monobutyl tin tris[cyclohexylidene bis (thio propionic acid) monobutyl ester]. Someexamples of monohydrocarbyl compounds having Z and Z unalike arebis(monobutyl tin diisooctylmercapto propionate) oxide and poly[butylstannoxy cyclohexylidene bis (thiopropionate) The monohydrocarbyl tincompounds are generally used in amounts varying from 1 to 25 weightpercent of the thioanhydride in stabilizers of the present invention andpreferably in amounts of 4 to 12 weight percent. The synergisticstabilizers of the present invention are generally incorporated into aresin in amounts of 0.1 to 10 weight percent and preferably from 0.5 toweight percent.

The synergistic action of the monohydrocarbyl tin compounds of thepresent invention is demonstrated to be unexpected in view of the poorresults obtained when diand trialkyl tin compounds are combined withorganic thioanhydride stabilizers.

Resins which may be stabilized by the synergistic composition of thepresent invention include both rigid and plastisized formulations ofhalogen containing polymers particularly polyvinyl chloride andvinylidene chloride, copolymers of halogen containing resins withethylenical- 1y unsaturated compounds such as, copolymers of vinylacetate and vinyl chloride and the like.

The following examples are presented to demonstrate several embodimentsof the present invention and are not to be considered as limitationsthereon.

EXAMPLE 1 Six formulations were prepared. Each formulation contained 100parts GEON 103P (a general purpose polyvinyl chloride resin suspensionmanufactured by the B. F. Goodrich Company), 0.5 parts of stearic acidand a total of 2 parts of the stabilizer as indicated in Table I. Eachformulation was processed on a two roll mill at 370 F. for five minutesand then divided into a number of 1" x b." x samples, the samples ofeach formulation were then placed in an air circulatory oven at 370 anda sample of each formulation was removed from the oven at minuteintervals over an interval of one hour. Formulations 1,3 and 5 weretested for comparative purposes and do not represent embodiments of thepresent invention. Table I reports the composition of the stabilizerstested with slight discoloration representing the time for someyellowing of the test sample to occur and moderate discolorationrepresenting the time for an orange or red discoloration to occur.

TABLE I Time in minutes to- Very slight Moderate Thermal Stabilizercomposition in discolordiscolor decompo- N0. parts of formulation (p.)ation ation sition 1 2.p. thiolaurie anhydride U) 10 2 {1.9 p.thiolaurie anhydride 00 0.1 p. butylstannoic acid- 3.. 2 p. thiostearicanhydride l) 10 4 {1.9 p. thiostearic anhydrid no 30 0.1 p.butylstannoic acid 5 2 p. thiobenzoic anhydride i0 .10 6 {1.9 p.thiobenzoic anhydride..1 30

""' 0.1 p. butylstannoic acid .l

I Yellowing began during milling.

In all three of the above formulations containing only thethioanhydride, early color developed during the milling operation, whilethe three formulations containing the synergistic combinations of thepresent invention exhibited no early color and began to show signs ofdegradation only after 20 minutes of exposure.

EXAMPLE 2 Six formulations, each containing 100 parts of PVC (a generalpurpose polyvinyl chloride resin manufactured 4 by the Diamond-ShamrockCorp.), 25 parts dioctylphthalate, 5 parts epoxidized soy bean oil, 0.25parts stearic acid and 2 parts of the respective stabilizers asindicated in Table II, were milled, divided and exposed according to theprocedure described in Example I. The results of the tests are reportedin Table II. Formulation I does not represent an embodiment of thepresent invention and is included only for comparative purposes andformulations 2-6 clearly demonstrate the improved results obtained usingthe stabilizers of the present invention.

TABLE II Time in minutes to- Very slight Moderate Substantial Stabilizercomposition in discolordiscolordiscolor- N 0. parts of formulation (p.)ation ation ation 1. 2 p. thiolauric anhydride 10 20 40 1.9 p.thiolauric anhydride. 0.1 p. Monobutyltin tris 2. [cyclohexylidene bis(thiopropionic acid) monobutyl ester}. 1.9 thiolauric anhydride 30.1p.Poly[buty1stannoxy 60 60 1 cyclohexylidene bis (thiopropionate)]. 4{1.9 p. thiolauric anhydride 50 0.1 p. butyl stannoic acid 5 {1.9 p.thiolauric anhydride 50 0.1 p. monobutyl tin sulfide-.. {1.9 p.thiolaurie anhydride 6 0.1 p. monobutyl tin tris 40 60 t ""1(isooctylmercapto propio- EXAMPLE 3 Eight formulations were prepared asdescribed in Example 2 except for the respective stabilizers asindicated in Table III and the formulations were processed in the samemanner described in Example 1 except oven exposure was extended thirtyminutes. The following table reports the results of the test withformulations 1 and 5 not being embodiments of the present invention andincluded for comparative purposes only.

TABLE 111 Time in minutes to Very I I slight Moderate Thermal Stabilizercomposition discoldiscolordegra- No. 1n parts (p.) oration ationdation 1. 2 p. thiostearie anhydride 10 51.9 p. thiostearie anhydride 1o30 90 "10.1 p. butylstannoic acid 3 ll.9 p. thiostearic anhydrideun} 1090 p. nfiethyl stanrgiczciiiufl p. t iostearic a y ri e... """101 p.phenylstannoic aeid 10 60 5..... thlilobgnzoic anhydlriidg 10 p. t toenzoic anhy ri e... ""{0.1 p. butylstannoic acid 10 60 7 (1.9 p.thiobenzoic anhydrid 10 50 ""891 P.1glftg3l5taflfgficg0ig p. t 0 enzoicay ri e '""(0.1 p. phenylstannoic acid.....} 20 80 90 l Slight yellowingdeveloped during milling.

Very strong discoloration after 10 minutes, decomposition at 80 minutes.

EXAMPLE 4 Three formulations were prepared containing parts of PVC 40 (ageneral purpose polyvinyl chloride resin manufactured by theDiamond-Shamrock Corp.), 25 parts dioctylphthalate, 5 parts epoxidizedsoy bean oil, 0.25 parts stearic acid and 2 parts of the respectivestabilizers listed in Table II were milled, divided and exposedaccording to the procedure described in Example 1 except that the ovenexposure was conducted for 90 minutes. The results of this test arereported in Table IV with formulation 2 being according to the presentinvention and formulations 1 and 3 not being embodiments of the presentinvention and included for comparative purposes to demonstrate thesynergistic effect of the stabilizers of the present invention.

liexylidene bis (thiopropionic acid) monobutyl ester] was substitutedfor the butyl stannoic acid in Example 6 and tests were extended toformulations containing up to 20 percent of the monobutyltin tris[cyclohexylidene bis(thi- TABLE Iv opropionic acid) monobutyl ester].The results of this test are reported in Table VII and formulation 1 isnot Tlme mmutest according to the present invention but included forcom- Ver rison r s sligh ti Moderate Thermal Pa Pu P0 es only Stabilizercomposition discoldiscolordegra- No. in parts (p.) oration ation dationTABLE I 2 p. thiolauric anhydride 10 20 90 VI 2 [1.9 p. thiolauricanhydride 50 Amount of s g-i g t i eig g 7;," w "5;, e Tm t fi t p. 11YS a 01C 801 0 Formulation $23 60 diseolgrizatiii n 1 Slight yellowingbegan during milling. 15

Q 1 0.05 O 30 EXAMPLE 5 0. 3 0. Six formulations more rigid than thoseof Examples 1-4 20 were prepared by mixing 100 parts of Opalan 630 (a 1y 1 n d 1 suspension of polyvinyl chloride manufactured by 20Shghtyenowmg deve mm Monsanto Corporation), 10 parts dioctylphthalate,parts epoxidized soy bean oil and 0.2 parts of stearic acid and EXAMPLE8 2.0 parts of the stabilizer as indicated in Table 5 was processedaccording to the procedure described in Ex- F f l ti f 100 parts tp 40,parts ample Table V reports the results of thls test; h octyl phthalate,5 parts epoxidized soy bean oil, 0.25 parts laIiOIl 1 is not anemhodimeht 0f the PTeSfint lhvenhoh of stearic acid, 1.9 partsthiolauric anhydride and 0.1 and is included comparatlve P p Y- parts ofthe stabilizer as indicated in Table VIII were processed according tothe procedure of Example 1. The TABLE v results of the test are reportedin Table VIII.

Time in minutes to slight No. Stabilizer composition in parts (p.)discoloration TABLE VIII 1 Fi' t S rious Ln" i bi tiiigiiftihfi lgliiihejjIIIIIIIIIIIIIL,. O Formulation Stabilizer composition co lardegradation 2. {0.1 p. monobutyltin tris [eyclohexylidene bis 30(thiopropionic acid) monobutyi ester]. 1 Butyl stannoic acid... 90 1.9p. thiolauric anhydride 2 Dioctyl tin bis(isooctyl t 3.-.-.{0.l1p.poly[bitt ]l stannoxy cyolohexlidene bis 30 3 D gggisgllattigkfiiajiu. t1 I18,

l.9 1 il iil)lauri: anhydride 30 4 Bis trlbutyl tin oxide 0 50 4 "'-l0.1p. butyl stannoic acid- 5 1.9 p. thiolauric anhydride 20 40 '"llLl p.llfklgnlobllityltllfi sailfgie.

loi eyl ifiin t rls (isooctylmercapto 20 The test of Example 8 clearlydemonstrates that only pmpionate) monohydrocarbyl tin compounds producethe synergistic 1 Developed during milling. respvlttls olitailned by thestabilizers of the present invention.

at c aim is: The formulation stabilized With thlolalllll'lc anhydride gi gg gg gggg fg g gigge ggig 0 ed earl olor durin the mi in o eration tilzl iltflff dlgtlnct ygil w color af%er 20 minufes of oven chlondeipollwmyhflhrle chlonde and copolymefs theTePf exposure while allformulations containing stabilizers of Yvlth other zy nlallyinsatufratfd mtclilnomclalrsdcrzimpristhe present invention did notdevelop early discoloration mg a clif T P i 0 a loan Y e until 20minutes of exposure to heat. reSPol'l mg to t 5 0mm a EXAMPLE 6 o Theprocedure of Example 5 was followed to prepare B four formulationsexcept that the amount of butylstannoic acid used as the co-stabilizerwith thiolauric anhydride h R d R h d was varied between 0 and 7 /2weight percent based on 2 26 b an d g 3' cagbyl radicals containing 6the thiolauric anhydride. Each formulation contained 2.0 2 car 0115 an aout to a out 15 'w ght percent or parts thiolauric anhydride aid theIflofllowii'ilg table reports rgu; az li s gg g gtygg l l o5: ggig ggafih gtigoglgfidile the results of the above test or eac ormu ation.carbyl radicals selected from the group consisting of TABLE VI alkyl,aryl, alkaryl and aralkyl radicals having 1 to 12 carbon atoms andbutyltin tris. glfilolultg Time in mm 2. A stabilizer according to claim1 wherein said thionoicicidin utes to Slight 6r anhydride is selectedfrom the group consisting of thio- Formu at o Dart per 100 discoloratlauric anhydride, thiostearic anhydride and thiobenzoic 1 0 i anhydride.2; 3. A stabilizer according to claim 2 wherein said mono-4IIIIIIIIIIIIII 0. is 20 hydrocarbyl tin compound is selected from thegroup Developed Slight yellow c0101. dumg mining consist ng of butylstannoic acid, monobutyl tiri tris methyl stannoic acid and phenylstannoic acid and said compound is present in an amount from about 4 toabout 12 EXAMPLE 7 weight percent. Six formulations were preparedaccording to the pro- 4. A composition comprising a halogen-containingpolycedure of Example 6 except that monobutyltin tris[cyclomer selectedfrom the group consisting of polyvinyl chlo- References Cited UNITEDSTATES PATENTS Weinberg 260-45.75 Hecker 260-4515 Frey 26045.75Hechenbleikner 260--45.7S

Stamm 26045.85

8 OTHER REFERENCES Chemistry and Industry, periodical dated Feb. 16,1963, pp. 271 and 279 of article entitled Antioxidants by Scott.

The Stabilization of Polyvinyl Chloride by Chevassus, 1963 edition, pp.166, 167 and 168. St. Martins Press, Inc., New York.

DONALD E. CZAJA, Primary Examiner V. P. HOKE, Assistant Examiner US. Cl.X.R.

UNITED STATES PATENT OFFICE QERTiFi-CATE OF CORRECTION Patent No.3,630,993 I Dated December 28, 1971 Inventor(s) Christian H. Stapfer Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

In claim 1, line 5 8, "or" should read --of--,' and in line 62, "tris."should read tris[cyc1oheXy1idene1, 1-bis (mercaptopropionate) monobutylester] In claim 3, line 70, "monobutyl tin tris" should read monobuty1tin tris[cyc1ohexy1idene bis (thiopropionic acid) monobutyl ester],-.

Signed and sealed this 18th day of December 1973.

(SEAL) Attest:

EDWARD M.PLETCHER,JR.

RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents FORMF'O-1050 (10-69) USCOMM-DC 60376-P69 1' us. GOVERNMENT PRINTING OFFICE1959 o-3ss-a34 UNITED STATES PATENT OFFICE CERTlFICATE OF CORRECTIONPatent No. 3,630,993 Dated December 28, 1971 Inventor(s) Christian H.Stapfer It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

In claim 1, line 58, "or" should read --of-, and in line 62, "tris.should read -tris[cyclohexylidenel, l-bis (mercaptopropionate) monobutylester] In claim 3, line 70, "monobutyl tin tris" should read -monobutyltin tris[cyclohexylidene bis (thiopropionic acid) monobutyl ester]',-. 1

Signed and sealed this 18th day of December 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR 7 RENE D. TEGTMEYER Attesting Officer ActingCommissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 6O376-P69 u.s.GOVERNMENT PRINTING OFFICE: 1969 0-366-334

